Manufacture of chloroform



Patented Apr. 21, 1931 UNITED STATES PATENT. OFFICE CHARLES .r.s'rnosncxnn, or MIDLAND, MICHIGAN, ASSIGNOR 'ro THE now CHEMICALCOMPANY, on MinLAnn, MICHIGAN, A, QORPORATION or MICHIGAN MANUFACTURE oroi-ironoromr No Drawing. Original application filed December 9, 1924,Serial No; 754,858. Divided and this application filed June 27, 1928.

The present improvements relating, as indicated, to the manufacture ofchloroform have more particular. regard to a method whereby suchchloroform may be made from trichlor-acetic acid (CChCOJ-I). WVhile thetheoretical possibility of such method of preparation may have received.consideration, I am not aware that such method has ever been foundfeasible for use in the comhot iZIlClllOI'iLCGlilC 201d." The limeshould mercial production of chloroform.

The object of the present invention accordingly is to provide arelatively simple and direct method for making chloroform wherel inacetic acid and chlorine, both of which are readily available, may beutilized as the basic ingredients in the process, viz., to maketrichlor-acetic acid, and the latter may then be converted simply anddirectly into the de-' sired final product. To the accomplishment.

of the foregoing and related ends, the invention, then, consists of thesteps hereinafter fully described and particularly pointed out in theclaims, the following description setting forth but several of thevarious Ways in which the principle of the invention may be used. 7

While trichlor-acetic acid may be variously prepared, I preferably makesuch'acid by direct chlorination of acetic acid, this method ofpreparation constituting a separate invention described and claimed inmy pending application filed Dec. 9, 1924, Serf #754,858 new Patent No.1,757,100, out of which the present application has been required to bedivided. It is known that monochlor-acetic acid may be prepared thus bydirectly chlorinating acetic acid. I have discovered that by conductingsuch chlorination in the presence of a catalyst such as aceticanhydride, sulphur, sulphur chloride, or phosphorus, and by continuingsuch chlorination at a somewhat higher temperature, the dichlor-compoundis obtained, and upon still further continuing the chlorination withcatalyst present at an elevated temperature, the trichlor-compound isobtained. The latter has a melting point (approximately 52 C.) higherthan normal room temperature and so Will solidify if allowed to cool tosuch temperature.

Serial No. 288,807.

Accordingto my present improved method of making chloroform, I then takesuch trlchlor-aceticacid while sufficiently hot to be fluid andpump sameinto a body ofmilk of lime, or equivalent hydroxlde compound.

be present in excess, the result of the reaction being the formation ofthe calcium saltof trichlor aoeticacidj as indicated by the followingequatiomviz Aftera suflicient quantityof such calciumv salt hasaccumulated, such salt being in suspension in the wateryvehicle thatformed the suspensionmedium for the milk of lime, the

resulting mixture is heated .to a. point of decomposition of such saltwith theformationofchloroform, as indicated by the following equation,viz V (2) Ga (001 500 +2H O- j v I i" Since no stage-wise vpurificationsare necessaryin this process, it will beseen thus that partiallychlorinated acetic acid, as for instance dichloracetic acid availablesometimes as a by-product n a process primar ly de-- signedforthepreparation of monochloracetic acid, can be conveniently-worked up withthe further chlorination as described and direct alkalination andsplitting to produce chloroform. r

The temperature in the final chlorination stage will run up from 150 to160 C. and,

such chlorination is carried to the point where from 85 to 90 per cent.of trichlor-acetic acid is formed. I have found that if it be attemptedto add more chlorine decomposition will occur. of trichlor-acetic acidinto chloroform may be accomplished at a temperature of from 50 to 0.,following which the chloroform is distilled off in the usual manner.

In place of adding the trichlor-acetic acid The decomposition of thecalcium salt i to milk of lime in the foregoing steps of the process, Imay add it to a water mixture or solution of other 11 droxides, forexample, the hydroxide of an al (ali or alkaline earth metal, or ofmagnesium; or the carbonate of any such metal may be substituted. Infact, the reactions set forth in Equations (1) and (2) above may becombined, eliminating the intermediary of any metal hydroxide anddirectly splitting off carbon dioxide, by similarly heating thetrichlor-acetic acid with the hydroxyl component, i. e. with water,alone, in accordance with the following equation,

This last mentioned reaction, however, proceeds too slowly to presentany practical value, as at present advised.

Other-modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the methodherein disclosed, provided the step or steps stated by any of thefollowing claims or the equivalent of such stated step or steps beemployed.

I therefore particularly point out and distinctly claim as my invention:

1. In a method of making chloroform, the steps whichconsist in reactingin an aqueous medium trichlor-acetic acid with calcium hydroxide, andthen heating the resultant solution or suspension to the point ofdecomposition of the calcium salt.

2. In a method of making chloroform, the steps which consist in reactingin an aqueous medium trichlor-acetic acid with calcium hydroxidesuspended in water, and then heating the resultant solution orsuspension to the point of decomposition of the calcium salt.

3. In a method of making chloroform, the steps which consist inintroducing trichloracetic acid into a suspension of calcium hydroxidein water, whereby the calcium salt of such acid is formed, cooling thesuspension during such introduction of the acid, then heating themixture at a temperature between about 50 to 60 C. and distilling offthe chloroform produced thereby.

Signed this 22nd day of June, 1928.

CHARLES J. STROSACKER.

